Three years, 1,000 charge cycles: how an iPhone 15 Pro Max battery is holding up

An iPhone completes one charge cycle when it uses 100 percent of its battery capacity, even if that happens across multiple charging sessions rather than one. The more cycles accumulate, the more chemically aged the battery becomes. Apple states that the iPhone 14 series and older are designed to retain 80 percent of original capacity at 500 cycles, while the iPhone 15 series and newer double that threshold to 1,000 cycles.

One Engadget writer's iPhone 15 Pro Max recently crossed exactly 1,000 charge cycles, with battery health currently reading 81 percent — technically still above Apple's threshold, but the wear is noticeable in daily use. Where the phone once lasted nearly two days with screen-on times exceeding 12 hours when new, it now often struggles to last until evening.

Software updates made things worse

According to the writer, software played a major role in the decline. iOS 17 ran smoothly, but iOS 18 brought complaints about poor performance, bugs and faster battery drain, worsened by Apple Intelligence features that heated the device. Things got worse still with iOS 26 and its "Liquid Glass" redesign, which slowed the phone down for nearly a full year. Relief came only with iOS 27, which focuses heavily on performance and stability: app launches are up to 30 percent faster, photos load up to 70 percent quicker, and AirDrop transfers are up to 80 percent faster.

The hardware has aged well

While the battery will likely need replacing, the rest of the phone has held up. The titanium frame and glass back still look nearly new despite mostly being used without a case, and the camera system, buttons and speakers all perform as well as they did at launch. Apple has since moved the iPhone 17 Pro series back to an aluminum chassis, but newer models, including the iPhone 18 Pro, reportedly scratch and dent more easily than the titanium generation did.